The purpose of this project is to investigate the cognitive and perceptual changes which are present in, and characteristics of, major affective illness. The present investigation comprises five separate ongoing studies: (1) psychomotor and psychosensory symptoms in affective illness, patients with complex partial seizures, and patient controls; (2) perception and recall of emotional and neutral stimuli in depression; (3) hypothesis testing in depression; (4) lateralized hemispheric function in depression; and (5) relationship of cognitive dysfunction to diagnostic subtype and neuroendocrine abnormalities in depression.